On tooth-flank scanning devices for testing and measuring the flanks of gears and similar parts, the respective flank is scanned by a scanner, which for this purpose is moved relative to the tooth flank. This movement occurs usually in the longitudinal direction of the tooth for testing the flank direction or in elevational direction of the tooth for testing the involute shape. The part of the scanner directly contacting the tooth flank, the scanner head, has in conventional devices, the shape of a truncated cone (German OS No. 32 12 082) or of a ball (German AS No. 23 64 917 and U.S. Pat. No. 3,936,946).
For testing and measuring of gears and gearlike gear-cutting tools, as for example gear-shaped cutters and bed drive pinions, such scanner heads have been successful for a long time. In gearlike tools with abrasive flank surfaces, as for example honing gears, grinding worms and the like, they deliver only unsatisfactory results. The truncated-cone-shaped scanner heads rest with the edge formed by the largest diameter of the truncated cone on the tooth flank. The edge representing an angle of about 60.degree. registers during the relative movement between tooth flank and scanner every irregularity, which in the case of abrasive surfaces are naturally very many. A so created recording chart does not make possible an unambiguous statement for example regarding the actual flank direction. A slightly stronger statement is provided by a recording chart on which is recorded data using a spherical scanner head. The size of the balls which can be used, however, have limits in particular in the case of small-modular tooth systems. Thus, in the case of a toothed tool for m. =2, only a ball having an approximately 1 to 1.5 mm. diameter can be introduced into a tooth space to near the dedendum circle without resting on both flanks. The smaller the ball, the more it registers roughness caused by the surface with the above-mentioned disadvantage, and the more it is exposed to wear by the abrasive surface. This wear occurs also with the truncated-cone-shaped scanner head.
Starting out from these deficiencies, the basic purpose of the invention is to provide a scanner head which is suited for testing and measuring the flanks of gears and similar parts, in particular of gearlike tools with abrasive flank surfaces. The scanner head is thereby also supposed to be usable for small-modular gears or tools.
To attain the purpose, a scanner head is provided which has a section which can be introduced or guided into a tooth space of the respective gear or similar part and which can be guided along one of the tooth flanks bordering the tooth space, the section being formed by the convex surface of a spherical segment, the radius of which is substantially larger than the radius of a ball introducible into the tooth space. Such a scanner head can be very small, since only a narrow cup and a thin support element need be introduced into the tooth space of the respective gear or tool. The large cup or ball radius does not register every unevenness on the tooth flank, but delivers a usable medium value. Furthermore, it is less susceptible to wear, since the contact pressure does not only act onto one projecting abrasive grain or the like, but is distributed onto several. The adjusting of the scanner head is made easier when the spherical segment is arranged on a holder mounted on the tooth-flank scanning device, which holder is pivotal about an axis which extends through the centerpoint of the ball, from which the spherical segment was formed, and perpendicularly to the direction of movement of the scanner head relative to the tooth flank to be scanned.